International
Tables for Crystallography Volume C Mathematical, physical and chemical tables Edited by E. Prince © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. C. ch. 9.7, pp. 899-900
|
Since both Kitajgorodskij's and Wilson's classifications were made with a view to `explaining' the empirically observed frequencies of space groups – though neither makes any use of empirical frequencies – it would be expected that there should be considerable correlation between them. All `closest-packed' space groups are also `fully antimorphic', and most of the `limitingly close packed' and `permissible' are `tending to antimorphism'; a few requiring high molecular symmetry (222, mm2, mmm) and a couple of others are `equally balanced'. Two `fully antimorphic' groups, Pc and Cc, are merely `permissible'. All `fully symmorphic' space groups are `impossible'.